ok, it looks like it is time for a new tutorial...
I have so many other things to do right now, so no video here

But a very quick answer:
1.) Why only 72 vertices ?:
When you create a sculptie, SUBSURF is enabled by default.
Furthermore SUBDIVISION LEVEL is set to "2"
Now what you call "the ghost object" is a virtual surface which is manipulated
by the 72 "vertices". In fact, when baking time has come, it is the "ghost object" which will be baked. And it HAS 1024 faces when you have used the default settings during creation time of the sculpt map. The good thing about using Subsurf is, that you almost can NOT fail with LOD. So your Sculpties will become automatically LOD safe and that is a good thing

On the other hand, you can not manipulate your ghost on a vertex level. But this is the price for automatic optimised LOD...
2.) If you want to get back to the "old style sculpties"
Then during creation of your sculptie disable "SUBSURF". And you are back to what you have seen before. Your Multires is back and you can work out your sculptie as you have
done before.
Now for the sculptie baking:
3.) I must admit that i do not know very much about the new options. So i keep them as they are and just klick on OK and i get the expected results.
one additional hint:
You can change the image , to which blender bakes the sculptie maps. But you can do that only when your 3D viewer is in edit mode. Then you can just go to the UV-editor, create a new image (preferably of size 64*64) and from now on the baker bakes to this new image.
Of course you can bake images of an arbitrary size (just create an image of 16*16) and your sculptie map still works ... or make it 256*256 and you get a big map (although it does not help you very much. In the general case you should stick with 64*64 sizes sculptie maps)
I hope, that helps a bit. A more comprehensive answer may come up soon
